MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
TREE FERNS (CYATHEALES) DIVERSITY IN THE APTIAN CERRO NEGRO FORMATION, LIVINGSTON ISLAND, ANTARCTICA
Autor/es:
CESARI, SILVIA NÉLIDA; VERA, EZEQUIEL IGNACIO
Lugar:
Florianópolis, Brasil
Reunión:
Simposio; XII Simpósio Brasileiro de Paleobotânica y Palinologia; 2008
Resumen:
In this contribution, we present a preliminary study about the diversity of tree ferns belonging to the Order Cyatheales recorded in the volcanoclastic outcrops of the Cerro Negro Formation at Livingston Island, South Shetland Islands, Antarctica, with an estimated age of ca. 120 MY. Impression/compression fossils described for the unit include Lophosoria cupulata, and Sergioa austrina, both presenting preserved sporangia containing Cyatheacidites-type spores, and Eocyatheae remasaliae, producer of Cyathidites-type spores. Preliminar studies on abundant (ca. 70) petrified stems reveal the presence of at least four different biological entities referable to the Order, including the anatomically-strange Alienopteris livingstonensis, and three taxa currently on study that present a mixture of characters previously unknown in living or fossil representatives of the clade. Furthermore, several stems preserve associated fronds and sporangia containing trilete spores. Finally, disperse spores assigned to the morphogenera Cyatheacidites and Cyathidites have been previously reported for the unit. This particular diversity of tree ferns brings support to the previously suggested frost-free palaeoclimatic conditions existing at the time of deposition of the Cerro Negro Formation.